Delayed 4 days!!

Hi I'm flying with jetstar to Hawaii in October, I had a phone call the other day to say my flight had been delayed, I thought oh a few hours or so on my way back home. No it had been delayed 4 days!!.... So I asked them where I was to stay and who would be paying for my hotel? Jetstar told me that it wasn't their responsibility to pay for my hotel, all they would offer me was a change of flight, which would mean me coming home earlier off my holiday or my money back on my flights which was not an option as I had my hotel and transfers paid for and I would risk not being able to get another flight on the days I wanted! I'm absolutely disgusted with how jetstar has handled my trouble, it has cost me $550 to stay extra 4days in Hawaii and $150 for a night in Melbourne as they couldn't give me a flight back to Adelaide on the same day I land in Melbourne. There seems to be no point of contact to make a complaint, I won't be travelling with jetstar again I would rather pay more for a more reliable and empathetic airline!!